Questions about valve guides
 

Is there a difference between bronze valve guides and bronze valve liners?
I would guess the bronze guides are the way to go in a marine engine?
When bronze guides are installed, do they pass completely through the head so that no original head material is touching any of the valve?

I have bronze guides that are pressed in from the spring side, but it appears that they end short of the bowl area by about a 1/4". Seems like it allows a small area that can still corrode against the valve stem if any moisture gets in. Is this correct?

Thanks.

yes, they do not contact the head of the valve, just support the stem, Rob

I guess what I am asking is, I have cast iron heads with bronze guides, but I see that towards the head side of the valve (nearest the combustion chamber), the valve stems pass through some of the original cast iron guide. The valve stem is not completely supported by bronze.

Is this correct? I have had valves hang in the guides and I can see a small amount of corrosion in the cast iron guide, beyond where the bronze guides end.

DO,
ARe you sure that the bronze guide does not go all the way through the head ?? Are they thin bronze "liners" or thicker totally bronze guides ? I am not sure that you could really install a solid bronze guide like you are describing, the tooling normally drills all the way through the head. Any chance of a picture ??

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Bill - I think you are right on - they do not go completely through the head and I think they were referred to as liners.

I assume the full bronze guide is the way it should be done in a marine engine?

I will see if I can get a picture.

Thanks

Sounds like from what you are describing you might need to find a better performance cylinder head shop for your head vork-valve jobs, valve guide replacements?
I know a lot of general automotive machine shops use bronze valve guide liners, but I think they are kind of like the old practice of knurling piston skirts to make them fit bigger bores,, not a great quality way of rebuilding heads with bronze guides.
In any event I would recommend you rework your marine heads with full size bronze valve guides of the proper size and length that have been installed so the end of the valve guide extends at least slightly below the level of the valve guide bore in the bowl area. Any sizing of the guide (not liner) where it does not extend to a proper length indicates a suspect job on the heads.
Take the time to do your heads right with a good shop, your engines are worthless without good heads and head work!

Best Regards,
Ray @ Raylar

Ray - thanks for your reply.

I agree 100%. I have had trouble with valves hanging and I suspect this is the problem.

DO,
Even with the thin wall bronze liners, they should go all the way through the head. I agree with Ray, I have never liked the thinwall liners but .... there are plenty of guys that use them, even in all out competition engines, without problems. I tried them a long time ago and just did not feel that you could get a consistant size on the id on them.